The present invention relates to a method for pipetting solution, and to a pipetting apparatus using the same, particularly, to the method for pipetting solution using detachable pipette tip, and the pipetting apparatus using the same.
In accordance with automatic analyzing apparatus for analyzing biological samples such as blood, urine, and the like, respective of the sample and reagents is added to a reaction vessel from sample pipetting apparatus and reagents pipetting apparatus, respectively, and a solution obtained by a reaction of the sample and the reagents is analyzed. The pipetting method can be divided roughly in two methods: the one is that the samples or the reagents are pipetted through a pipette nozzle, and the pipette nozzle is repeatedly used by washing wall of the pipette touched with the sample or the reagent; the other one is that the sample or the reagents are pipetted through a disposable tip provided at the tip of the pipetting probe, and the tip is changed at every pipetting operation.
When a designated amount of the sample or the reagent is sucked into the disposable tip provided at the tip of the pipetting probe and the sucked sample or the reagent is discharged into a container, the sample or the reagent is remained slightly on the inner wall of the tip. The amount of the sample or the reagent remained on the inner wall of the tip after discharging varies depending on the surface condition of the inner wall of the tip. The surface condition of the inner wall varies based on respective of the disposable tip, and accordingly, the amount of discharged sample or the reagent, which must be substantially definite, is varied.
JP-A-6-289032 (1994) relating to this technical field discloses a method for pipetting, wherein the surface condition 10 of the respective tips is made uniform by sucking and discharging the sample or the reagent preliminarily in a condition that the disposable tip is immersed into a solution of the sample or the reagent, before pipetting the sample or the reagent.
However, the method disclosed in JP-A-6-289032 (1994) has a problem that an excess amount of the sample or the reagent is adhered onto the inner wall of the tip, because the sample or the reagent themselves are sucked and discharged preliminarily, and the excess amount of the sample or the reagent can be discharged into the reaction vessel.
The one of the objects of the present invention is to provide a pipetting apparatus, which can be operated without performing the preliminary suction and discharge of the sample or the reagent, i.e. the objects of the pipetting, by the disposable tip, before pipetting operation.
The other one of the objects of the present invention is to provide a pipetting apparatus, which can pipette an exact amount of the sample or the reagent when the disposable tip is used.
The one of the concept of the present invention is featured in comprising the steps of: transferring a tubular probe, which is provided with the pipetting apparatus and attachable with disposable pipette tip, toward a high humidity chamber; introducing high humid air in the high humidity chamber into the probe; sucking objective solution of the pipetting into the pipette tip from a container by transferring the pipette tip toward the container in the condition that the high humid air is contained in the pipette tip attached to the probe; subsequently, transferring the pipette tip toward the other container; discharging the objective solution of the pipetting, which has been sucked in the pipette tip, into the other container; and detaching the pipette tip used in the pipetting from the pipetting apparatus.
In accordance with a desirable embodiment of the present invention, a pipette tip is attached with the probe for attaching the pipette tip before transferring to the high humid chamber, and subsequently, the high humid air is introduced into the probe through the pipette tip. Otherwise, the high humid air is introduced into the probe for attaching the pipette tip before attaching the probe to the pipette tip, subsequently, the pipette tip is attached with the probe, and then, the high humid air in the probe is transferred into the pipette tip.
In accordance with the desirable embodiment, the objective solution is the sample or the reagent, and the relative humidity of the high humid air introduced into the pipette tip is at least 80%.
The other one of the concept of the present invention is featured in a pipetting method for pipetting an objective solution from a container to another container using a disposable pipette tip comprising the steps of; filling a tubular probe, which is provided with the pipetting apparatus and can be attached with a disposable pipette tip, with pressure transmission medium liquid supplied from a liquid transferring apparatus connected to the tubular probe; introducing a designated amount of air into the probe by moving the medium solution backward before or after attaching the pipette tip to the probe ; subsequently, a designated amount of air is released through the pipette tip in order to remain high humid air in the pipette tip; then, the objective solution of pipetting is sucked into the pipette tip from a container, and adding the objective solution of pipetting into the other container.
In accordance with the desirable embodiment of the present invention, the amount of air introduced into the probe is more than the capacity of the pipette tip, and the amount of air released from the pipette tip is less than the amount of air introduced into the pipette tip and the probe. Temperature at the tip storage portion for storing the pipette tip before attaching to the probe is maintained in the range from 4 to 10 degrees Celsius.